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Zones 1A, 1B, 2A, 2B, 3A, 3B, 6-16, 18-24
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Calylophus

Sundrops
Onagraceae
Perennials

Western natives related to and much resembling evening primrose (Oenothera), with bright yellow, four-petaled flowers over a long summer bloom period. Plants are 1–2 ft. tall. In Zone 13, flowering declines in summer heat, and plants flower in spring and from late summer to fall. Plants spread by rhizomes and are useful for summer color in difficult climates. Shear just before spring growth begins. Plant in well-drained soil. They tolerate regular water if drainage is superb.

Calylophus drummondianus (photo courtesy of Proven Winners)
Calylophus drummondianus (photo courtesy of Proven Winners)

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Calylophus drummondianus

Grows to 1 1/2 ft. high, 2 ft. wide, with narrow, tooth-edged, somewhat drooping leaves and inch-wide flowers. This species blooms for a longer period than C. hartwegii in spring, but it does not rebloom as well in fall.

Calylophus hartwegii fendleri (photo courtesy of Annie’s Annuals & Perennials)
Calylophus hartwegii fendleri (photo courtesy of Annie’s Annuals & Perennials)

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Calylophus hartwegii fendleri

Grows up to 1 ft. high, 2 ft. across, with inch-wide flowers; those of ‘Sierra Sundrop’ are larger. Calylophus hartwegii lavandulifolius (C. lavandulifolius) has narrow, gray leaves. Excellent in hot, dry locations and when mixed with desert perennials.

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